Whisk the eggs, vegetable oil, and vanilla in a large bowl. Add the chocolate cake mix and stir until a thick, sticky dough forms, then fold in the mini chocolate chips if using.

Cover the bowl and chill the dough for at least 20 minutes. Chilling makes the dough easier to scoop and helps the cookies keep their shape in the oven.

Heat the oven to 350°F and line two baking sheets with parchment paper. Scoop about 1 1/2 tablespoons of dough for each cookie and roll into balls.

Roll each dough ball generously in powdered sugar until fully coated. Place the balls about 2 inches apart on the prepared baking sheets.

Bake for 9 to 11 minutes, until the cookies are puffed and visibly cracked but still soft in the centers. Let them cool on the baking sheets for 5 minutes before transferring to a wire rack.